عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The present study was carried out to investigate the effect of corn replacement by different levels of wheat with supplementation of phytase with reduced phosphorus level for laying hens. Two hundred seventy nine layer hens (the strains of Hy-line W36) at the 53th week of age, selected based on the same egg production percentage and body weight, assigned in a factorial arrangement with completely randomized design of 30 treatments each in 3 replicates. The factors included 5 levels of replacements (0, 25, 50, 75, 100% replacement of corn by wheat), phytase enzyme in three levels (0, 500, 1000 ftu/kg) and two levels of non phytate phosphorus (0.70% and 0.55% requirement) along with one corn soybean meal control diet. The experiment was carried out at 3 periods, each of 28 days. Egg production percentage, egg weight, feed conversion ratio, shell percentage, shell strength, shell thickness and toe ash were assessed. The results indicated that the effects of substitution wheat on egg production, Feed Conversion Ratio (FCR), shell strength, shell thickness and toe ash were significant (P<0.05), with on increase of wheat in the diet, egg production, and toe ash being improved. FCR in the 75% substitution of wheat treatment was decreased while in the 100% substitution it was increased. Eggshell percentage wasn't affected by substitution of wheat. Effect of enzyme on egg production percentage, egg weight, FCR, shell strength, shell thickness and toe ash was significant (P<0.01). The effect of non phytate phosphorus level on egg production was significant (P<0.05). Egg weight, FCR, shell percentage, shell thickness and toe ash weren't affected by non phytate phosphorus level. Results suggested that a deficiency of non-phytate phosphorus isn’t problematic and a utilization of 50% corn substitution with wheat along with supplemental 500ftu/kg phytase would improve the performance and therefore, corn cab be replaced by wheat to a level of 75%.